Solid-state imaging device, method of manufacturing the same, and electronic device

ABSTRACT

The present technology relates to a solid-state imaging device capable of inhibiting peeling of a fixed charge film while inhibiting dark current, a method of manufacturing the same, and an electronic device. A solid-state imaging device provided with a semiconductor substrate in which a plurality of photodiodes is formed, a groove portion formed in a depth direction from a light incident side for forming an element separating unit between adjacent photoelectric conversion elements on the semiconductor substrate, a first fixed charge film formed so as to cover a surface of a planar portion on the light incident side of the semiconductor substrate, and a second fixed charge film formed so as to cover an inner wall surface of the groove portion formed on the semiconductor substrate is provided. The present technology is applicable to a backside illumination CMOS image sensor, for example.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage application under 35 U.S.C. 371 andclaims the benefit of PCT Application No. PCT/JP2015/081269 having aninternational filing date of 6 Nov. 2015, which designated the UnitedStates, which PCT application claimed the benefit of Japanese PatentApplication No. 2014-233312 filed 18 Nov. 2014, the disclosures of whichare incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present technology relates to a solid-state imaging device, a methodof manufacturing the same, and an electronic device, and especiallyrelates to the solid-state imaging device capable of inhibiting peelingof a fixed charge film while inhibiting dark current, the method ofmanufacturing the same, and the electronic device.

BACKGROUND ART

Recently, a backside illumination solid-state imaging device in whichlight is applied from a side opposite to a side on which a wiring layeris formed on a semiconductor substrate is suggested (for example, referto Patent Document 1). In the solid-state imaging device disclosed inPatent Document 1, an element separating unit for electricallyseparating pixels is formed on a boundary of adjacent pixels formed onthe semiconductor substrate.

CITATION LIST Patent Document

Patent Document 1: Japanese Patent Application Laid-Open No. 2012-191005

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Although a groove portion for forming an element separating unit isformed by dry etching in general in a solid-state imaging device, aninterface state due to a crystal defect, dangling bond and the likeincreases and dark current is likely to be generated on a surface(especially, an inner peripheral surface and a bottom surface of thegroove portion) of a semiconductor substrate processed by the dryetching.

Therefore, a method of forming a negative fixed charge film on a surfaceof a planar portion of the semiconductor substrate and the innerperipheral surface and the bottom surface of the groove portion forinhibiting an increase and generation of the dark current is known;however, a phenomenon that the fixed charge film is peeled on thesemiconductor substrate occurs.

The present technology is achieved in consideration of such a condition,and an object thereof is to satisfy both inhibition of the dark currentand inhibition of peeling of the fixed charge film in the solid-stateimaging device.

Solutions to Problems

A solid-state imaging device according to a first aspect of the presenttechnology is a solid-state imaging device including a semiconductorsubstrate in which a plurality of photoelectric conversion element isformed, a groove portion formed in a depth direction from a lightincident side for forming an element separating unit between adjacentphotoelectric conversion elements on the semiconductor substrate, afirst fixed charge film formed to cover a surface of a planar portion onthe light incident side of the semiconductor substrate, and a secondfixed charge film formed to cover an inner wall surface of the grooveportion formed on the semiconductor substrate.

In the solid-state imaging device according to the first aspect of thepresent technology, a plurality of photoelectric conversion element isformed in the semiconductor substrate, the groove portion is formed inthe depth direction from the light incident side for forming the elementseparating unit between the adjacent photoelectric conversion elementson the semiconductor substrate, the first fixed charge film is formed tocover the surface of the planar portion on the light incident side ofthe semiconductor substrate, and the second fixed charge film is formedto cover the inner wall surface of the groove portion formed on thesemiconductor substrate.

A manufacturing method according to a second aspect of the presenttechnology is a manufacturing method including steps of forming a grooveportion in a depth direction from a light incident side by etching forforming an element separating unit between adjacent photoelectricconversion elements on a semiconductor substrate in which a plurality ofphotoelectric conversion elements is formed, forming a second fixedcharge film according to an amount of damage received by an inner wallsurface of the groove portion from the etching so as to cover the innerwall surface of the groove portion formed on the semiconductorsubstrate, and forming a first fixed charge film according to an amountof damage received by a planar portion from the etching so as to cover asurface of the planar portion on the light incident side of thesemiconductor substrate.

According to the manufacturing method according to the second aspect ofthe present technology, the groove portion is formed in the depthdirection from the light incident side by etching for forming theelement separating unit between the adjacent photoelectric conversionelements on the semiconductor substrate in which a plurality ofphotoelectric conversion elements is formed, the second fixed chargefilm according to the amount of the damage received by the inner wallsurface of the groove portion from the etching is formed so as to coverthe inner wall surface of the groove portion formed on the semiconductorsubstrate, and the first fixed charge film according to the amount ofthe damage received by the planar portion from the etching is formed soas to cover the surface of the planar portion on the light incident sideof the semiconductor substrate.

A manufacturing method according to a third aspect of the presenttechnology is a manufacturing method including steps of forming a firstfixed charge film according to an amount of damage received by a planarportion from etching for forming a groove portion on a semiconductorsubstrate so as to cover a surface of the planar portion on a lightincident side of the semiconductor substrate in which a plurality ofphotoelectric conversion elements is formed, forming the groove portionin a depth direction from the light incident side by the etching forforming an element separating unit between adjacent photoelectricconversion elements on the semiconductor substrate covered with thefirst fixed charge film, and forming a second fixed charge filmaccording to an amount of damage received by an inner wall surface ofthe groove portion from the etching so as to cover the inner wallsurface of the groove portion formed on the semiconductor substrate.

In the manufacturing method according to the third aspect of the presenttechnology, the first fixed charge film according to the amount of thedamage received by the planar portion from etching for forming thegroove portion on the semiconductor substrate is formed so as to coverthe surface of the planar portion on the light incident side of thesemiconductor substrate in which a plurality of photoelectric conversionelements is formed, the groove portion is formed in the depth directionfrom the light incident side by the etching for forming the elementseparating unit between the adjacent photoelectric conversion elementson the semiconductor substrate covered with the first fixed charge film,and the second fixed charge film according to the amount of the damagereceived by the inner wall surface of the groove portion from theetching is formed so as to cover the inner wall surface of the grooveportion formed on the semiconductor substrate.

An electronic device according to a fourth aspect of the presenttechnology is an electronic device including a solid-state imagingdevice including a semiconductor substrate in which a plurality ofphotoelectric conversion elements is formed, a groove portion formed ina depth direction from a light incident side for forming an elementseparating unit between adjacent photoelectric conversion elements onthe semiconductor substrate, a first fixed charge film formed so as tocover a surface of a planar portion on the light incident side of thesemiconductor substrate, and a second fixed charge film formed so as tocover an inner wall surface of the groove portion formed on thesemiconductor substrate.

In the solid-state imaging device provided in the electronic deviceaccording to the fourth aspect of the present technology, a plurality ofphotoelectric conversion elements is formed in the semiconductorsubstrate, the groove portion is formed in the depth direction from thelight incident side for forming the element separating unit between theadjacent photoelectric conversion elements on the semiconductorsubstrate, the first fixed charge film is formed so as to cover thesurface of the planar portion on the light incident side of thesemiconductor substrate, and the second fixed charge film is formed soas to cover the inner wall surface of the groove portion formed on thesemiconductor substrate.

Effects of the Invention

According to the first to fourth aspects of the present technology, itis possible to inhibit peeling of a fixed charge film while inhibitingdark current.

Meanwhile, the effects are not necessarily limited to the effects hereindescribed and may include any of the effects described in the presentdisclosure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating a configuration example of a solid-stateimaging device.

FIG. 2 is an enlarged cross-sectional view illustrating a part of thesolid-state imaging device.

FIG. 3 is a view illustrating a cross-sectional structure of a peripheryof a first element separating unit.

FIG. 4 is a view illustrating a cross-sectional structure of a peripheryof a second element separating unit.

FIG. 5 is a view illustrating a flow of a first manufacturing step.

FIG. 6 is a view schematically illustrating each step at the firstmanufacturing step.

FIG. 7 is a view illustrating a cross-sectional structure of a peripheryof a third element separating unit.

FIG. 8 is a view illustrating a cross-sectional structure of a peripheryof a fourth element separating unit.

FIG. 9 is a view illustrating a cross-sectional structure of a peripheryof a fifth element separating unit.

FIG. 10 is a view illustrating a flow of a second manufacturing step.

FIG. 11 is a view schematically illustrating each step at the secondmanufacturing step.

FIG. 12 is a view illustrating a cross-sectional structure of aperiphery of a sixth element separating unit.

FIG. 13 is a view illustrating a cross-sectional structure of aperiphery of a seventh element separating unit.

FIG. 14 is a view illustrating a cross-sectional structure of aperiphery of an eighth element separating unit.

FIG. 15 is a view illustrating a configuration example of an electronicdevice including a solid-state imaging device.

FIG. 16 is a view illustrating a usage example of a solid-state imagingdevice.

MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present technology are hereinafter described withreference to the drawings. Meanwhile, the description is given in thefollowing order.

1. First Embodiment (Solid-state Imaging Device)

2. Second Embodiment (Solid-state Imaging Device)

3. Variation

4. Configuration of Electronic Device

5. Usage Example of Solid-state Imaging Device

<1. First Embodiment>

(Configuration of Solid-state Imaging Device)

FIG. 1 is a view illustrating a configuration example of a solid-stateimaging device.

A solid-state imaging device 10 in FIG. 1 is, for example, an imagesensor such as a complementary metal oxide semiconductor (CMOS) imagesensor. The solid-state imaging device 10 captures incident light (imagelight) from an object through an optical lens system (not illustrated)and converts an amount of the incident light an image of which is formedon an imaging surface to an electric signal in a pixel unit to output asa pixel signal.

In FIG. 1, the solid-state imaging device 10 includes a pixel array unit21, a vertical driving circuit 22, a column signal processing circuit23, a horizontal driving circuit 24, an output circuit 25, a controlcircuit 26, and an input/output terminal 27.

Unit pixels 31 are arranged to form a two-dimensional array in the pixelarray unit 21. The unit pixel 31 includes a photodiode as aphotoelectric conversion element and a plurality of pixel transistors.

The vertical driving circuit 22 formed of a shift register, for example,selects predetermined pixel driving wiring 41 and supplies a pulse fordriving the unit pixel 31 to the selected pixel driving wiring 41 todrive the unit pixels 31 row by row. That is to say, the verticaldriving circuit 22 sequentially selects to scan the unit pixels 31 ofthe pixel array unit 21 row by row in a vertical direction and suppliesthe pixel signal based on a signal charge generated according to anamount of received light in the photoelectric conversion element of eachunit pixel 31 to the column signal processing circuit 23 through avertical signal line 42.

The column signal processing circuits 23 arranged for respective columnsof the unit pixels 31 perform signal processing such as noise removal onthe signals output from the unit pixels 31 of one row for respectivepixel columns. For example, the column signal processing circuit 23performs the signal processing such as correlated double sampling (CDS)for removing a fixed pattern noise peculiar to a pixel and analogdigital (AD) conversion.

The horizontal driving circuit 24 formed of a shift register, forexample, selects the column signal processing circuits 23 in turn bysequentially outputting horizontal scanning pulses and allows each ofthe column signal processing circuits 23 to output the pixel signal to ahorizontal signal line 43.

The output circuit 25 performs signal processing on the signalssequentially supplied from the respective column signal processingcircuits 23 through the horizontal signal line 43 to output. There is acase in which the output circuit 25 merely buffers, for example, or acase in which this performs black level adjustment, column variationcorrection, various types of digital signal processing and the like.

The control circuit 26 receives an input clock signal and data orderingan operation mode and the like and outputs data of internal informationand the like of the solid-state imaging device 10. That is to say, thecontrol circuit 26 generates a clock signal and a control signal servingas a reference of operation of the vertical driving circuit 22, thecolumn signal processing circuit 23, the horizontal driving circuit 24and the like on the basis of a vertical synchronization signal, ahorizontal synchronization signal, and a master clock signal. Then, thecontrol circuit 26 outputs the generated clock signal and control signalto the vertical driving circuit 22, the column signal processing circuit23, the horizontal driving circuit 24 and the like.

The input/output terminal 27 communicates signals with the outside.

The solid-state imaging device 10 in FIG. 1 configured in theabove-described manner is the CMOS image sensor referred to as a columnAD type in which the column signal processing circuit 23 which performsCDS processing and AD conversion processing is arranged for each pixelcolumn.

(Detailed Structure of Solid-state Imaging Device)

Next, a detailed structure of the solid-state imaging device 10 in FIG.1 is described. FIG. 2 is an enlarged cross-sectional view illustratinga part of the solid-state imaging device 10. In FIG. 2, a backsideillumination CMOS image sensor is illustrated as the solid-state imagingdevice 10.

In FIG. 2, the unit pixel 31 forms one pixel out of the two-dimensionalarray in the pixel array unit 21 in the solid-state imaging device 10.Also, in FIG. 2, a wiring layer 130 and a supporting substrate 110 areformed on a front surface side (surface S2 side in the drawing) of asemiconductor substrate 121 forming a light receiving layer 120 and alight condensing layer 140 is formed on a back surface side (surface S1side in the drawing) of the semiconductor substrate 121. Meanwhile,pixel transistors such as a transfer transistor, a reset transistor, anamplification transistor, and a selection transistor are formed on thefront surface side of the semiconductor substrate 121.

In the light receiving layer 120, the semiconductor substrate 121 isformed of p-type silicon (Si), for example, in which a photodiode 122 asthe photoelectric conversion element is buried. Also, in the lightreceiving layer 120, a groove portion 121A extending in a depthdirection (Z direction) of the semiconductor substrate 121 is formedbetween the unit pixels on the back surface side (surface S1 side in thedrawing) of the semiconductor substrate 121.

A planar portion 121B (on the back surface side (light incident side))of the semiconductor substrate 121 and the groove portion 121A formed onthe semiconductor substrate 121 are covered with a negative fixed chargefilm such as a first fixed charge film 123A or a second fixed chargefilm 123B. Then, an insulating film 124, an antireflection film 125, aninsulating film 126, and a light shielding film 142 are buried in thisorder in the groove portion 121A covered with the negative fixed chargefilm to form an element separating unit 127. That is to say, the elementseparating unit 127 is formed into a lattice shape so as to enclose theunit pixel 31, and the photodiodes 122 are electrically separated fromone another by the element separating units 127.

Herein, in the semiconductor substrate 121, the first fixed charge film123A is formed to cover all or a large part of a surface of the planarportion 121B and the second fixed charge film 123B is formed to coverall or a large part of a bottom surface and an inner peripheral surfaceof the groove portion 121A. Meanwhile, the bottom surface and the innerperipheral surface of the groove portion 121A are hereinaftercollectively referred to as an “inner wall surface”.

The negative fixed charge film according to an amount of damage whichthe planar portion 121B receives from etching for forming the grooveportion 121A on the semiconductor substrate 121 is used as the firstfixed charge film 123A. For example, as the first fixed charge film123A, a material such as a hafnium oxide (HfO₂) film deposited on theplanar portion 121B of the semiconductor substrate 121 to inhibitoccurrence of blister, the material which is not peeled from the planarportion 121B is preferably used.

The negative fixed charge film according to an amount of damage whichthe inner wall surface of the groove portion 121A receives from theetching for forming the groove portion 121A on the semiconductorsubstrate 121 is used as the second fixed charge film 123B. For example,as the second fixed charge film 123B, a material such as an aluminumoxide (Al₂O₃) film deposited on the semiconductor substrate 121 togenerate a fixed charge, thereby strengthening pinning of the grooveportion 121A is preferably used.

Meanwhile, a high refractive index material film or a high dielectricfilm having a negative charge, that is to say, an oxide or a nitridecontaining at least one element out of hafnium (Hf), aluminum (Al),zirconium (Zr), tantalum (Ta), and titanium (Ti), for example, may beapplied to the second fixed charge film 123B.

The insulating film 124 is formed so as to be buried in the grooveportion 121A covered with the second fixed charge film 123B. Theinsulating film 124 is preferably formed of a material having arefractive index different from that of the second fixed charge film123B such as an oxide film, for example. Meanwhile, silicon oxide(SiO₂), silicon nitride (Si₃N₄), silicon oxynitride (SiON), a resin orthe like may be used, for example, as the material of the insulatingfilm 124.

The antireflection film 125 is formed on the first fixed charge film123A and a part thereof is buried in the groove portion 121A. Aninsulating film (low reflection film) having an optical function such asa silicon nitride film (Si₃N₄) may be used, for example, as a materialof the antireflection film 125. The insulating film 126 is formed on theantireflection film 125 and a part thereof is buried in the grooveportion 121A. An oxide film and the like may be used, for example, as amaterial of the insulating film 126.

The light shielding film 142 is formed in a predetermined region on theinsulating film 126 buried in the groove portion 121A and is formed intoa lattice shape so as to form opening on the photodiode 122 in a pixelregion. A material which shields light may be used as a material of thelight shielding film 142; for example, aluminum (Al), tungsten (W),copper (Cu) or the like may be used.

A planarizing film 143 is formed on an entire insulating film 126including the light shielding film 142. According to this, a surface onthe back surface side of the semiconductor substrate 121 is planarized.An organic material such as a resin may be used, for example, as amaterial of the planarizing film 143.

A color filter layer 144 is formed on the planarizing film 143. Thecolor filter layer 144 is formed so as to correspond to red (R), green(G), and blue (B), for example, for respective unit pixels 31. Light ofa desired wavelength is transmitted through the color filter layer 144and transmitted light is incident on the photodiode 122 formed in thesemiconductor substrate 121.

An on-chip lens 141 is formed on the color filter layer 144. Irradiationlight is condensed by the on-chip lens 141 and the condensed light isefficiently incident on the photodiode 122 efficiently through the colorfilter layer 144.

The on-chip lens 141, the color filter layer 144, the planarizing film143, and the light shielding film 142 form the light condensing layer140 on the back surface side (surface S1 side in the drawing) of thesemiconductor substrate 121. Also, the wiring layer 130 formed on thefront surface side (surface S2 side in the drawing) of the semiconductorsubstrate 121 is formed of wiring 132A to wiring 132C stacked to form aplurality of layers (three layers in FIG. 2) through an interlayerinsulating film 131. The pixel transistor of the unit pixel 31 is driventhrough the wiring 132 formed in the wiring layer 130.

The supporting substrate 110 is formed on a side opposite to a sidefacing the semiconductor substrate 121 of the wiring layer 130. Thesupporting substrate 110 formed for securing strength of thesemiconductor substrate 121 in a manufacturing phase is formed of asilicon substrate, for example.

In the solid-state imaging device 10 having the above-describedconfiguration, light is applied from the back surface side of thesemiconductor substrate 121 and the light transmitted through theon-chip lens 141 and the color filter layer 144 is subjected tophotoelectric conversion by the photodiode 122, so that the signalcharge is generated. Then, the signal charge generated by the photodiode122 is output as the pixel signal through a signal line formed ofpredetermined wiring 132 in the wiring layer 130 through the pixeltransistor formed on the front surface side of the semiconductorsubstrate 121.

(Detailed Structure of Element Separating Unit)

Next, a detailed structure of the element separating unit 127 in FIG. 2is described. A detailed structure of a first element separating unit127-1 corresponding to the element separating unit 127 in FIG. 2 and adetailed structure of a second element separating unit 127-2 as avariation thereof are herein described.

(Cross-sectional Structure of First Element Separating Unit)

FIG. 3 is a view illustrating a cross-sectional structure of a peripheryof the first element separating unit 127-1.

In the first element separating unit 127-1 in FIG. 3, the groove portion121A is formed in the depth direction from the back surface side of thesemiconductor substrate 121 and the inner wall surface thereof iscovered with the first and second fixed charge films 123A and 123B.

Specifically, in the first element separating unit 127-1, the bottomsurface of the groove portion 121A is covered with the second fixedcharge film 123B. On the other hand, although the large part of theinner peripheral surface of the groove portion 121A is covered with thesecond fixed charge film 123B, a part on a side near the planar portion121B of the semiconductor substrate 121 is covered with the first fixedcharge film 123A. Also, the surface of the planar portion 121B of thesemiconductor substrate 121 is covered with the first fixed charge film123A. That is to say, on the surface (silicon surface) of thesemiconductor substrate 121, the negative fixed charge film is switchedfrom the first fixed charge film 123A to the second fixed charge film123B in a certain portion in the groove portion 121A.

In the first element separating unit 127-1, the insulating film 124 isformed in the groove portion 121A covered with the first and secondfixed charge films 123A and 123B. An upper portion (upper surface) ofthe insulating film 124 is covered with the first fixed charge film123A. Also, the antireflection film 125 and the insulating film 126 areformed on the first fixed charge film 123A to have a concave shapecorresponding to a dug portion of the groove portion 121A. Then, thelight shielding film 142 is formed so as to be buried in the concaveportion.

As described above, in the semiconductor substrate 121 on which thefirst element separating unit 127-1 is formed, the inner wall surface ofthe groove portion 121A and the surface of the planar portion 121B arecovered with any one of two types of negative fixed charge films 123having different characteristics. For example, when the aluminum oxide(Al₂O₃) film is used as the second fixed charge film 123B covering theinner wall surface of the groove portion 121A formed on thesemiconductor substrate 121, the pinning is strengthened and occurrenceof dark current may be inhibited. Also, for example, when the hafniumoxide (HfO₂) film is used as the first fixed charge film 123A coveringthe surface of the planar portion 121B of the semiconductor substrate121, the occurrence of the blister is inhibited and peeling of thenegative fixed charge film from the planar portion 121B may beinhibited. As a result, it is possible to satisfy both inhibition of thedark current and inhibition of the peeling of the fixed charge film inthe solid-state imaging device 10.

A reason why such an effect may be obtained is as follows in detail.That is to say, the groove portion 121A of the element separating unit127-1 formed into a lattice shape so as to enclose the unit pixel 31 isformed by dry etching in general, and it is known that an interfacestate due to a crystal defect, dangling bond and the like increases andthe dark current is likely to be generated on the surface (especially,the bottom surface and the inner peripheral surface of the grooveportion 121A) of the semiconductor substrate 121 processed by the dryetching. Also, although it is required to form a narrower groove portion121A in order to downsize the unit pixel 31 and form a deeper grooveportion 121A in order to inhibit color mixing; however, when bothrequirements are satisfied, the damage due to the dry etching increasesin general and the dark current tends to increase due to an increase incrystal defect and dangling bond.

When the inner wall surface of the groove portion 121A formed on thesemiconductor substrate 121 and the surface of the planar portion 121Bof the semiconductor substrate 121 are covered with the same negativefixed charge film (for example, the aluminum oxide (Al₂O₃) film) inorder to inhibit the increase and generation of the dark current,hydrogen of a terminal group of silicon and at the time of stacking anupper layer structure is accumulated on an interface between the fixedcharge film and silicon and the fixed charge film is peeled on theplanar portion 121B of the semiconductor substrate 121. Incidence of thepeeling of the fixed charge film differs depending on a planar directionof silicon; the peeling is less likely to occur on a processed surfacesuch as the groove portion 121A but likely to occur on the planarportion 121B.

Then, in the present technology, different negative fixed charge filmsare used to cover the inner wall surface of the groove portion 121A andto cover the surface of the planar portion 121B depending on the damageamounts focusing on difference in crystal defect and dangling bondamounts due to difference in the amount of the damage received from thedry etching for forming the groove portion 121A on the semiconductorsubstrate 121 between the inner wall surface of the groove portion 121Aformed on the semiconductor substrate 121 and the surface of the planarportion 121B of the semiconductor substrate 121.

That is to say, the negative fixed charge film (for example, thealuminum oxide (Al₂O₃) film and the like) according to the amount of thedamage which the inner wall surface of the groove portion 121A receivesfrom the dry etching is used as the second fixed charge film 123Bcovering the inner wall surface of the groove portion 121A, and thenegative fixed charge film (for example, the hafnium oxide (HfO₂) filmand the like) according to the amount of the damage which the planarportion 121B receives from the dry etching is used as the first fixedcharge film 123A covering the surface of the planar portion 121B.According to this, the generation of the dark current is inhibited bythe second fixed charge film 123B covering the inner wall surface of thegroove portion 121A and the peeling of the fixed charge film may beinhibited by the first fixed charge film 123A covering the surface ofthe planar portion 121B.

For comparison, when the inner wall surface of the groove portion 121Aand the surface of the planar portion 121B are covered only with thefirst fixed charge film 123A (for example, the hafnium oxide (HfO₂) filmand the like) in the first element separating unit 127-1, the peeling ofthe fixed charge film may be inhibited but the generation of the darkcurrent cannot be inhibited. On the other hand, when the inner wallsurface of the groove portion 121A and the surface of the planar portion121B are covered only with the second fixed charge film 123B (forexample, the aluminum oxide (Al₂O₃) film and the like) in the firstelement separating unit 127-1, the generation of the dark current may beinhibited but the peeling of the fixed charge film cannot be inhibited.

In this manner, although strengthening of the pinning of the grooveportion 121A formed on the semiconductor substrate 121 and theinhibition of the occurrence of the blister on the planar portion 121Bof the semiconductor substrate 121 are in a trade-off relationship, itis possible to satisfy both the inhibition of the dark current and theinhibition of the peeling of the fixed charge film in the solid-stateimaging device 10 by adopting the structure of the first elementseparating unit 127-1 in FIG. 3.

Meanwhile, although a shape of the groove portion 121A is illustrated tobe a trapezoidal shape narrowing in the depth direction from the backsurface side of the semiconductor substrate 121 in FIG. 3, this shape isnot limited to the trapezoidal shape but may also be a rectangularshape, for example. The same applies to other drawings to be describedlater.

(Cross-sectional Structure of Second Element Separating Unit)

FIG. 4 is a view illustrating a cross-sectional structure of a peripheryof a second element separating unit 127-2.

In FIG. 4, as compared to the first element separating unit 127-1 inFIG. 3, the second element separating unit 127-2 has the innerperipheral surface covered with the first fixed charge film 123A and theinner peripheral surface covered with the second fixed charge film 123Bwith different widths in the groove portion 121A formed on thesemiconductor substrate 121.

Specifically, in the second element separating unit 127-2, the bottomsurface of the groove portion 121A is covered with the second fixedcharge film 123B. On the other hand, although the large part of theinner peripheral surface of the groove portion 121A is covered with thesecond fixed charge film 123B, a part with a larger width on a side nearthe planar portion 121B of the semiconductor substrate 121 is coveredwith the first fixed charge film 123A. Also, the surface of the planarportion 121B of the semiconductor substrate 121 is covered with thefirst fixed charge film 123A. That is to say, on the surface (siliconsurface) of the semiconductor substrate 121, the negative fixed chargefilm is switched from the first fixed charge film 123A to the secondfixed charge film 123B in a portion in which the groove portion 121Abecomes narrower.

In the semiconductor substrate 121 on which the second elementseparating unit 127-2 having the above-described structure is formed,the blister occurring on the planar portion 121B is inhibited by thefirst fixed charge film 123A formed of the hafnium oxide (HfO₂) film andthe like, for example, and in contrast, the pinning of the grooveportion 121A is strengthened by the second fixed charge film 123B formedof the aluminum oxide (Al₂O₃) film and the like, for example. As aresult, it is possible to satisfy both inhibition of the dark currentand inhibition of the peeling of the fixed charge film in thesolid-state imaging device 10.

(First Manufacturing Step)

Next, a first manufacturing step of forming the first element separatingunit 127-1 in FIG. 3 is described.

FIG. 5 is a view illustrating a flow of the first manufacturing step.Meanwhile, schematic diagrams corresponding to respective steps in FIG.5 are illustrated in FIG. 6 and it is described with reference to theschematic diagrams appropriately.

At step S11, an antireflection film forming step is performed. At theantireflection film forming step, as illustrated in A of FIG. 6, a lowantireflection film 151 is formed on the semiconductor substrate 121.

At step S12, a photoresist opening step is performed. At the photoresistopening step, as illustrated in B of FIG. 6, a photoresist 152 is formedon the low antireflection film 151 formed at the step at step S11 andopened. This opening is made for forming the groove portion 121A betweenthe unit pixels 31; a width thereof may be set to approximately 0.1 μmto 0.3 μm, for example, depending on the size of the unit pixel 31.

A silicon groove forming step is performed at step S13. At the silicongroove forming step, as illustrated in C of FIG. 6, the dry etching isperformed on the photoresist 152 opened at the step at step S12, therebyopening the low antireflection film 151 to further form the grooveportion 121A on the semiconductor substrate 121 formed of silicon (Si).

Meanwhile, it is sufficient that the groove portion 121A has a depthwith which cross-talk may be controlled; this is, for example, not lessthan 0.25 μm and not greater than 5 μm. Also, it is sufficient that thegroove portion 121A has a width with which the cross-talk may becontrolled; this is, for example, not less than 100 nm and not greaterthan 1000 nm.

A step of forming the second fixed charge film and the like is performedat step S14. At the step of forming the second fixed charge film and thelike, as illustrated in D of FIG. 6, the inner wall surface of thegroove portion 121A formed at the step at step S13 and the surface ofthe planar portion 121B of the semiconductor substrate 121 are coveredwith the second fixed charge film 123B and are further blocked with theinsulating film 124 deposited by atomic layer deposition (ALD).

Meanwhile, at that time, the inner wall surface of the groove portion121A formed at the step at step S13 is significantly damaged by the dryetching, so that the negative fixed charge film with stronger pinningaccording to the damage amount (for example, the aluminum oxide (Al₂O₃)film and the like) is used as the second fixed charge film 123B.

At step S15, an etching step is performed. At the etching step, asillustrated in E of FIG. 6, the second fixed charge film 123B and theinsulating film 124 on the planar portion 121B and the like of thesemiconductor substrate 121 formed at the step at step S14 are removedby the dry etching or wet etching to expose the semiconductor substrate121.

A step of forming the first fixed charge film and the like is performedat step S16. At the step of forming the first fixed charge film and thelike, as illustrated in F of FIG. 6, the first fixed charge film 123A isformed by chemical vapor deposition (CVD) including the atomic layerdeposition (ALD) or physical vapor deposition (PVD) in a hollow of thegroove portion 121A formed at the step at step S15.

Meanwhile, the blister might occur on the planar portion 121B of thesemiconductor substrate 121, so that the negative fixed charge filmcapable of inhibiting the occurrence of the blister (for example, thehafnium oxide (HfO₂) film and the like) is used according to the damageamount by the dry etching at the step at step S13 as the first fixedcharge film 123A. Also, at the step of forming the first fixed chargefilm and the like, the antireflection film 125 and the insulating film126 are further formed on the first fixed charge film 123A asillustrated in F of FIG. 6.

At step S17, a light shielding film forming step is performed. At thelight shielding film forming step, as illustrated in G of FIG. 6, thelight shielding film 142 is formed on the insulating film 126 formed atthe step at step S16.

At step S18, a light shielding film processing step is performed. At thelight shielding film processing step, the light shielding film 142formed at the step at step S17 is removed by etching such that only aportion of a predetermined region corresponding to the groove portion121A is left. According to this, the first element separating unit 127-1including the light shielding film 142 is formed into a lattice shape soas to open on the photodiode 122 in the pixel region.

The first manufacturing step is heretofore described.

Meanwhile, although the case in which the first element separating unit127-1 in FIG. 3 is formed is described at the above-described firstmanufacturing step, the second element separating unit 127-2 in FIG. 4may also be similarly formed. That is to say, when the second elementseparating unit 127-2 is formed, the groove portion 121A may be formedon the semiconductor substrate 121 such that the width of the innerperipheral surface covered with the first fixed charge film 123A isdifferent from the width of the inner peripheral surface covered withthe second fixed charge film 123B at the silicon groove forming step atstep S13 in FIG. 5, for example.

Also, it becomes possible to form a structure to form different fixedcharge films of two or more types on the inner peripheral surface of thegroove portion 121A formed on the semiconductor substrate 121 by usingthe above-described first manufacturing step. It is also possible todirectly form the photoresist 152 on the semiconductor substrate 121without forming the low antireflection film 151 on the semiconductorsubstrate 121 while omitting the step at step S11.

<2. Second Embodiment>

(Detailed Structure of Element Separating Unit)

Although a case in which a part of an inner peripheral surface of agroove portion 121A formed on a semiconductor substrate 121 is coveredwith a first fixed charge film 123A is described in the above-describedfirst embodiment, it is also possible that the inner peripheral surfaceof the groove portion 121A is covered only with a second fixed chargefilm 123B. Therefore, a case in which an inner wall surface of thegroove portion 121A formed on the semiconductor substrate 121 is coveredonly with the second fixed charge film 123B and a surface of a planarportion 121B of the semiconductor substrate 121 is covered with thefirst fixed charge film 123A is next described as a second embodiment.

A detailed structure of a third element separating unit 127-3 as thesecond embodiment and detailed structures of fourth and fifth elementseparating units 127-4 and 127-5 as variations thereof are hereindescribed.

(Cross-sectional Structure of Third Element Separating Unit)

FIG. 7 is a view illustrating a cross-sectional structure of a peripheryof the third element separating unit 127-3.

In the third element separating unit 127-3 in FIG. 7, the groove portion121A is formed in a depth direction from a back surface side of thesemiconductor substrate 121 and the inner wall surface thereof iscovered with the second fixed charge film 123B. Also, in the grooveportion 121A, an insulating film 124 is formed on the inner wall surfacecovered with the second fixed charge film 123B and a light shieldingfilm 142 is further buried therein.

Also, in FIG. 7, the surface of the planar portion 121B of thesemiconductor substrate 121 is covered with the first fixed charge film123A. Furthermore, an antireflection film 125 and an insulating film 126are formed on the first fixed charge film 123A.

In the semiconductor substrate 121 on which the third element separatingunit 127-3 having the above-described structure is formed, blisteroccurring on the planar portion 121B is inhibited by the first fixedcharge film 123A formed of a hafnium oxide (HfO₂) film and the like, forexample, and in contrast, pinning of the groove portion 121A isstrengthened by the second fixed charge film 123B formed of an aluminumoxide (Al₂O₃) film and the like, for example. As a result, it ispossible to satisfy both inhibition of the dark current and inhibitionof the peeling of the fixed charge film in the solid-state imagingdevice 10.

(Cross-sectional Structure of Fourth Element Separating Unit)

FIG. 8 is a view illustrating a cross-sectional structure of a peripheryof the fourth element separating unit 127-4.

In FIG. 8, the fourth element separating unit 127-4 is different fromthe third element separating unit 127-3 in FIG. 7 in that only theinsulating film 124 is buried in the inner wall surface of the grooveportion 121A covered with the second fixed charge film 123B. The lightshielding film 142 is formed on the insulating film 124 buried in thegroove portion 121A.

Also, in FIG. 8, the surface of the planar portion 121B of thesemiconductor substrate 121 is covered with the first fixed charge film123A. Furthermore, the antireflection film 125 and the insulating film126 are formed on the first fixed charge film 123A.

In the semiconductor substrate 121 on which the fourth elementseparating unit 127-4 having the above-described structure is formed,the blister occurring on the planar portion 121B is inhibited by thefirst fixed charge film 123A formed of the hafnium oxide (HfO₂) film andthe like, for example, and in contrast, the pinning of the grooveportion 121A is strengthened by the second fixed charge film 123B formedof the aluminum oxide (Al₂O₃) film and the like, for example. As aresult, it is possible to satisfy both inhibition of the dark currentand inhibition of the peeling of the fixed charge film in thesolid-state imaging device 10.

(Cross-sectional Structure of Fifth Element Separating Unit)

FIG. 9 is a view illustrating a cross-sectional structure of a peripheryof the fifth element separating unit 127-5.

In FIG. 9, the fifth element separating unit 127-5 is different from thethird element separating unit 127-3 in FIG. 7 in that the second fixedcharge film 123B and the insulating film 124 formed on the inner wallsurface of the groove portion 121A are further deposited on an uppersurface of the antireflection film 125 and the insulating film 126formed on the first fixed charge film 123A covering the surface of theplanar portion 121B of the semiconductor substrate 121.

Also, in FIG. 9, in the groove portion 121A formed on the semiconductorsubstrate 121, as is the case with the fourth element separating unit127-4 in FIG. 8, only the insulating film 124 is buried in the innerwall surface covered with the second fixed charge film 123B.

In the semiconductor substrate 121 on which the fifth element separatingunit 127-5 having the above-described structure is formed, the blisteroccurring on the planar portion 121B is inhibited by the first fixedcharge film 123A formed of the hafnium oxide (HfO₂) film and the like,for example, and in contrast, the pinning of the groove portion 121A isstrengthened by the second fixed charge film 123B formed of the aluminumoxide (Al₂O₃) film and the like, for example. As a result, it ispossible to satisfy both inhibition of the dark current and inhibitionof the peeling of the fixed charge film in the solid-state imagingdevice 10.

(Second Manufacturing Step)

Next, a second manufacturing step of forming the third elementseparating unit 127-3 in FIG. 7 is described.

FIG. 10 is a view illustrating a flow of the second manufacturing step.Meanwhile, schematic diagrams corresponding to respective steps in FIG.10 are illustrated in FIG. 11 and it is described with reference to theschematic diagrams appropriately.

At step S31, a step of forming the first fixed charge film and the likeis performed. At the step of forming the first fixed charge film and thelike, as illustrated in A of FIG. 11, the first fixed charge film 123Ais formed on the surface of the planar portion 121B of the semiconductorsubstrate 121. Meanwhile, the blister might occur on the planar portion121B of the semiconductor substrate 121, so that a film capable ofinhibiting the blister such as the hafnium oxide (HfO₂) film, forexample, is used as the first fixed charge film 123A.

Also, at the step of forming the first fixed charge film and the like,the antireflection film 125 and the insulating film 126 are furtherformed on the first fixed charge film 123A. Meanwhile, the insulatingfilm 126 is herein deposited by a thickness obtained by adding athickness required as a processing residual film and a thickness lostwhen the groove portion 121A is formed on the semiconductor substrate121.

At step S32, a photoresist opening step is performed. At the photoresistopening step, as illustrated in B of FIG. 11, a photoresist 152 isformed on the insulating film 126 formed at the step at step S31 andopened. The opening is made for forming a groove between unit pixels 31;a width thereof may be set to approximately 0.1 μm to 0.3 μm, forexample, depending on a size of the unit pixel 31.

At step S33, a silicon groove forming step is performed. At the silicongroove forming step, as illustrated in C of FIG. 11, dry etching isperformed, for example, on the photoresist 152 opened at the step atstep S32, thereby opening the insulating film 126, the antireflectionfilm 125, and the first fixed charge film 123A, and further forming thegroove portion 121A on the semiconductor substrate 121 formed of silicon(Si).

Meanwhile, a depth of the groove is set to depth and width required forinhibiting cross-talk. Also, at the silicon groove forming step, thefirst fixed charge film 123A, an upper layer film thereof, and silicon(Si) may be separately opened. When the step at step S33 is finished, acleaning step is performed, and thereafter, a step at step S34 isperformed.

A second fixed charge film forming step is performed at step S34. At thesecond fixed charge film forming step, as illustrated in D of FIG. 11,the second fixed charge film 123B is formed by chemical vapor deposition(CVD) on the inner wall surface of the groove portion 121A formed at thestep at step S33 and an upper surface of the insulating film 126 formedon the planar portion 121B of the semiconductor substrate 121.

Meanwhile, herein, the groove portion 121A formed at the step at stepS33 is significantly damaged by the dry etching, so that a film withstronger pinning such as the aluminum oxide (Al₂O₃) film, for example,is used as the second fixed charge film 123B covering the inner wallsurface thereof.

At step S35, an insulating film forming step is performed. At theinsulating film forming step, as illustrated in E of FIG. 11, theinsulating film 124 is formed on the second fixed charge film 123Bformed at the step at step S34 by atomic layer deposition.

At step S36, a light shielding film forming step is performed. At thelight shielding film forming step, as illustrated in F of FIG. 11, thelight shielding film 142 is formed on the insulating film 124 formed atthe step at step S35.

At step S37, a film processing step is performed. At the film processingstep, as illustrated in G of FIG. 11, a part of the second fixed chargefilm 123B formed at the step at step S34, the insulating film 124 formedat the step at step S35, and the light shielding film 142 formed at thestep at step S36 is removed by etching such that only a portion of apredetermined region corresponding to the groove portion 121A is left.

The second manufacturing step is heretofore described.

Meanwhile, although the case in which the third element separating unit127-3 in FIG. 7 is formed is described at the above-described secondmanufacturing step, the fourth element separating unit 127-4 in FIG. 8and the fifth element separating unit 127-5 in FIG. 9 may also besimilarly formed. That is to say, when the fourth element separatingunit 127-4 is formed, for example, the groove portion 121A covered withthe second fixed charge film 123B may be buried (blocked) only with theinsulating film 124 at the insulating film forming step at step S35 inFIG. 10.

Also, when the fifth element separating unit 127-5 is formed, forexample, etching may be performed such that a part of the second fixedcharge film 123B and the insulating film 124 is left on the planarportion 121B of the semiconductor substrate 121 at the film processingstep at step S37 in FIG. 10.

In this manner, the light shielding film 142 finally separating the unitpixels 31 is processed on the planar portion 121B of the semiconductorsubstrate 121 to realize interpixel light shielding; the second fixedcharge film 123B is further located below the insulating film 124serving as bedding after the light shielding film 142 is processed. Thesecond fixed charge film 123B may be left as-is; however, if sensitivitymight be deteriorated due to difference in reflective index from theinsulating film 124, this may be removed at the time of film processingstep for realizing the interpixel light shielding by the light shieldingfilm 142 (S37 in FIG. 10).

<3. Variation>

(Detailed Structure of Element Separating Unit)

Although detailed structures of third to fifth element separating units127-3 to 127-5 are described in the above-described second embodiment,detailed structures of sixth, seventh, and eighth element separatingunits 127-6, 127-7, and 127-8 are herein described as further variationsof the second embodiment.

(Cross-sectional Structure of Sixth Element Separating Unit)

FIG. 12 is a view illustrating a cross-sectional structure of aperiphery of the sixth element separating unit 127-6.

In FIG. 12, as compared to the fourth element separating unit 127-4 inFIG. 8, the sixth element separating unit 127-6 is such that aninsulating film 126 formed on a first fixed charge film 123A and anantireflection film 125 is removed by etching with only a portion of apredetermined region corresponding to a second fixed charge film 123B,an insulating film 124, and a light shielding film 142 left on a planarportion 121B of a semiconductor substrate 121.

Also, in FIG. 12, in a groove portion 121A formed on the semiconductorsubstrate 121, as is the case with the fourth element separating unit127-4 in FIG. 8, only the insulating film 124 is buried in an inner wallsurface covered with the second fixed charge film 123B and the lightshielding film 142 is further formed on the insulating film 124.

In the semiconductor substrate 121 on which the sixth element separatingunit 127-6 having the above-described structure is formed, blisteroccurring on the planar portion 121B is inhibited by the first fixedcharge film 123A formed of a hafnium oxide (HfO₂) film and the like, forexample, and in contrast, pinning of the groove portion 121A isstrengthened by the second fixed charge film 123B formed of an aluminumoxide (Al₂O₃) film and the like, for example. As a result, it ispossible to satisfy both inhibition of the dark current and inhibitionof the peeling of the fixed charge film in the solid-state imagingdevice 10.

(Cross-sectional Structure of Seventh and Eighth Element SeparatingUnits)

FIG. 13 is a view illustrating a cross-sectional structure of aperiphery of the seventh element separating unit 127-7. Also, FIG. 14 isa view illustrating a cross-sectional structure of a periphery of theeighth element separating unit 127-8.

In FIG. 13, as compared to the fourth element separating unit 127-4 inFIG. 8, the seventh element separating unit 127-7 is such that a largepart of a surface of the planar portion 121B of the semiconductorsubstrate 121 is covered with the first fixed charge film 123A, but apart on a side near the groove portion 121A is covered with the secondfixed charge film 123B as is the case with the inner wall surface of thegroove portion 121A.

Meanwhile, although it is required to cover the large part of thesurface of the planar portion 121B of the semiconductor substrate 121with the first fixed charge film 123A in order to inhibit occurrence ofthe blister, it is also possible to enlarge a portion covered with thesecond fixed charge film 123B on the surface of the planar portion 121Bas illustrated in FIG. 14 as long as the occurrence of the blister maybe inhibited.

Also, in FIG. 13, in the groove portion 121A formed on the semiconductorsubstrate 121, as is the case with the fourth element separating unit127-4 in FIG. 8, only the insulating film 124 is buried in the innerwall surface covered with the second fixed charge film 123B and thelight shielding film 142 is further formed on the insulating film 124.

In the semiconductor substrate 121 on which the seventh or eighthelement separating unit 127-7 or 127-8 having the above-describedstructure is formed, the blister occurring on the planar portion 121B isinhibited by the first fixed charge film 123A formed of the hafniumoxide (HfO₂) film and the like, for example, and in contrast, thepinning of the groove portion 121A is strengthened by the second fixedcharge film 123B formed of the aluminum oxide (Al₂O₃) film and the like,for example. As a result, it is possible to satisfy both inhibition ofthe dark current and inhibition of the peeling of the fixed charge filmin the solid-state imaging device 10.

<4. Configuration of Electronic Device>

The present technology is not necessarily applied to a solid-stateimaging device. That is to say, the present technology is applicable toelectronic devices including the solid-state imaging device in generalsuch as a camera module including an optical lens system and the like inaddition to the solid-state imaging device, an imaging device such as adigital still camera and a video camera, a portable terminal devicehaving an imaging function (for example, a smartphone and a tabletterminal), or a copying machine in which the solid-state imaging deviceis used in an image reading unit.

FIG. 15 is a block diagram illustrating a configuration example of theelectronic device including the solid-state imaging device.

An electronic device 300 in FIG. 15 is the electronic device such as theimaging device such as the digital still camera and the video camera,the portable terminal device such as the smartphone and the tabletterminal and the like, for example.

In FIG. 15, the electronic device 300 is formed of a solid-state imagingdevice 301, a DSP circuit 302, a frame memory 303, a display unit 304, arecording unit 305, an operating unit 306, and a power supply unit 307.Also, in the electronic device 300, the DSP circuit 302, the framememory 303, the display unit 304, the recording unit 305, the operatingunit 306, and the power supply unit 307 are connected to one another viaa bus line 308.

The solid-state imaging device 301 captures incident light (image light)from an object through an optical lens system (not illustrated) andconverts an amount of the incident light an image of which is formed onan imaging surface to an electric signal in a pixel unit to output as apixel signal.

Also, the solid-state imaging device 301 corresponds to a solid-stateimaging device 10 in FIG. 1 and a cross-sectional structure in FIG. 2 isadopted, for example, as a structure thereof. That is to say, in thesolid-state imaging device 301, a surface of a planar portion 121B of asemiconductor substrate 121 is covered with a first fixed charge film123A such as a hafnium oxide (HfO₂) film, for example, and an inner wallsurface of a groove portion 121A formed on the semiconductor substrate121 is covered with a second fixed charge film such as an aluminum oxide(Al₂O₃) film, for example.

The DSP circuit 302 is a camera signal processing circuit whichprocesses the signal supplied from the solid-state imaging device 301.The frame memory 303 temporarily holds image data processed by the DSPcircuit 302 in a frame unit.

The display unit 304 formed of a panel display device such as a liquidcrystal panel and an organic electro luminescence (EL) panel, forexample, displays a moving image or a still image taken by thesolid-state imaging device 301. The recording unit 305 records imagedata of the moving image or the still image taken by the solid-stateimaging device 301 in a recording medium such as a semiconductor memoryand a hard disk.

The operating unit 306 issues an operation order regarding variousfunctions of the electronic device 300 in accordance with operation by auser. The power supply unit 307 appropriately supplies various powersources serving as operation power sources of the DSP circuit 302, theframe memory 303, the display unit 304, the recording unit 305, and theoperating unit 306 to supply targets.

The electronic device 300 is formed in the above-described manner. Inthe solid-state imaging device 301 of the electronic device 300, anegative fixed charge film covering the surface of the planar portion121B of the semiconductor substrate 121 and the negative fixed chargefilm covering the inner wall surface of the groove portion 121A formedon the semiconductor substrate 121 which are different from each otherare used according to an amount of damage received from dry etching forforming the groove portion 121A, so that it is possible to inhibitpeeling of the fixed charge film while inhibiting dark current.

<5. Usage Example of Solid-state Imaging Device>

FIG. 16 is a view illustrating a usage example of a solid-state imagingdevice 10 as an image sensor.

The above-described solid-state imaging device 10 may be used in variouscases in which light such as visible light, infrared light, ultravioletlight, and X-ray is sensed as described below, for example. That is tosay, as illustrated in FIG. 16, the solid-state imaging device 10 may beused in devices used in a traffic field, a home appliance field, amedical care and health care field, a security field, a beauty carefield, a sports field, or an agricultural field, for example, inaddition to a field of appreciation in which an image to be appreciatedis taken described above.

Specifically, as described above, the solid-state imaging device 10 maybe used in a device for taking an image to be appreciated (electronicdevice 300 in FIG. 15, for example) such as a digital camera, asmartphone, and a cell phone having a camera function, for example, inthe field of appreciation.

In the traffic field, the solid-state imaging device 10 may be used indevices used for traffic such as a vehicle-mounted sensor which takesimages of the front, back, surroundings, and inside of an automobile, amonitoring camera which monitors running vehicles and roads, and aranging sensor which measures a distance between vehicles for safedriving such as automatic stop and recognition of a driver's condition,for example.

In the home appliance field, the solid-state imaging device 10 may beused in home appliances such as a television receiver, a refrigerator,and an air conditioner for taking an image of a user's gesture andoperating the device according to the gesture, for example. Also, in themedical care and health care field, the solid-state imaging device 10may be used in medical care and health care devices such as an endoscopeand a device performing angiography by receiving infrared light, forexample.

In the security field, the solid-state imaging device 10 may be used insecurity devices such as a security monitoring camera and a personalauthentication camera, for example. Also, in the beauty care field, thesolid-state imaging device 10 may be used in beauty care devices such asa skin measuring device which takes an image of skin and a microscopewhich takes an image of head skin, for example.

In the sports field, the solid-state imaging device 10 may be used insports devices such as an action camera and a wearable camera forsports, for example. Also, in the agricultural field, the solid-stateimaging device 10 may be used in agricultural devices such as a camerafor monitoring a land and crop state, for example.

Meanwhile, the embodiments of the present technology are not limited tothe above-described embodiments and various modifications may be madewithout departing from the scope of the present technology. For example,it is possible to adopt a mode obtained by combining all or some of aplurality of embodiments described above.

The present technology may also have the following configurations.

(1)

A solid-state imaging device including:

a semiconductor substrate in which a plurality of photoelectricconversion elements is formed;

a groove portion formed in a depth direction from a light incident sidefor forming an element separating unit between adjacent photoelectricconversion elements on the semiconductor substrate;

a first fixed charge film formed to cover a surface of a planar portionon the light incident side of the semiconductor substrate; and

a second fixed charge film formed to cover an inner wall surface of thegroove portion formed on the semiconductor substrate.

(2)

The solid-state imaging device according to (1), wherein

the first fixed charge film is a first negative fixed charge film, and

the second fixed charge film is a second negative fixed charge filmdifferent from the first negative fixed charge film.

(3)

The solid-state imaging device according to (2), wherein

a large part of an inner peripheral surface is covered with the secondnegative fixed charge film and a remaining part of the inner peripheralsurface is covered with the first negative fixed charge film on theinner wall surface of the groove portion formed on the semiconductorsubstrate.

(4)

The solid-state imaging device according to (2), wherein

a large part of the surface of the planar portion is covered with thefirst negative fixed charge film and a remaining part of the surface ofthe planar portion is covered with the second negative fixed charge filmon the planar portion on the light incident side of the semiconductorsubstrate.

(5)

The solid-state imaging device according to any one of (2) to (4),wherein

the first negative fixed charge film is the negative fixed charge filmaccording to an amount of damage received by the planar portion frometching for forming the groove portion on the semiconductor substrate,and

the second negative fixed charge film is the negative fixed charge filmaccording to an amount of damage received by the inner wall surface ofthe groove portion from the etching.

(6)

The solid-state imaging device according to any one of (1) to (5),wherein

a light shielding film is formed on the groove portion formed on thesemiconductor substrate.

(7)

The solid-state imaging device according to (6), wherein

the light shielding film is formed of aluminum (Al) or tungsten (W).

(8)

The solid-state imaging device according to any one of (1) to (7),wherein

the solid-state imaging device is a backside illumination complementarymetal oxide semiconductor (CMOS) image sensor,

a light condensing layer is formed on a back surface side of thesemiconductor substrate, and

a wiring layer is formed on a front surface side of the semiconductorsubstrate.

(9)

A manufacturing method including steps of:

forming a groove portion in a depth direction from a light incident sideby etching for forming an element separating unit between adjacentphotoelectric conversion elements on a semiconductor substrate in whicha plurality of photoelectric conversion elements is formed;

forming a second fixed charge film according to an amount of damagereceived by an inner wall surface of the groove portion from the etchingso as to cover the inner wall surface of the groove portion formed onthe semiconductor substrate; and

forming a first fixed charge film according to an amount of damagereceived by a planar portion from the etching so as to cover a surfaceof the planar portion on the light incident side of the semiconductorsubstrate.

(10)

A manufacturing method including steps of:

forming a first fixed charge film according to an amount of damagereceived by a planar portion from etching for forming a groove portionon a semiconductor substrate so as to cover a surface of the planarportion on a light incident side of the semiconductor substrate in whicha plurality of photoelectric conversion elements is formed;

forming the groove portion in a depth direction from the light incidentside by the etching for forming an element separating unit betweenadjacent photoelectric conversion elements on the semiconductorsubstrate covered with the first fixed charge film; and

forming a second fixed charge film according to an amount of damagereceived by an inner wall surface of the groove portion from the etchingso as to cover the inner wall surface of the groove portion formed onthe semiconductor substrate.

(11)

An electronic device including:

a solid-state imaging device including:

a semiconductor substrate in which a plurality of photoelectricconversion elements is formed;

a groove portion formed in a depth direction from a light incident sidefor forming an element separating unit between adjacent photoelectricconversion elements on the semiconductor substrate;

a first fixed charge film formed so as to cover a surface of a planarportion on the light incident side of the semiconductor substrate; and

a second fixed charge film formed so as to cover an inner wall surfaceof the groove portion formed on the semiconductor substrate.

REFERENCE SIGNS LIST

-   10 Solid-state imaging device-   21 Pixel array unit-   31 Unit pixel-   110 Supporting substrate-   120 Light receiving layer-   121 Semiconductor substrate-   121A Groove portion-   121B Planar portion-   122 Photodiode-   123A First fixed charge film-   123B Second fixed charge film-   124 Insulating film-   125 Antireflection film-   126 Insulating film-   127 Element separating unit-   130 Wiring layer-   131 Interlayer insulating film-   132 Wiring-   140 Light condensing layer-   141 On-chip lens-   142 Light shielding film-   143 Planarizing film-   144 Color filter film-   300 Electronic device-   301 Solid-state imaging device

What is claimed is:
 1. A solid-state imaging device comprising: asemiconductor substrate in which a plurality of photoelectric conversionelements are formed; a groove portion formed in a depth direction from alight incident side for forming an element separating unit betweenadjacent photoelectric conversion elements on the semiconductorsubstrate; a first fixed charge film formed to cover a surface of aplanar portion formed according to an amount of damage received frometching for forming the groove portion on the light incident side of thesemiconductor substrate, wherein the first fixed charge film is a firstnegative fixed charge film; and a second fixed charge film formed tocover an inner wall surface of the groove portion formed according to anamount of damage received from the etching for forming the grooveportion formed on the semiconductor substrate, wherein the second fixedcharge film is a second negative fixed charge film different from thefirst negative fixed charge film.
 2. The solid-state imaging deviceaccording to claim 1, wherein a large part of an inner peripheralsurface is covered with the second negative fixed charge film and aremaining part of the inner peripheral surface is covered with the firstnegative fixed charge film on the inner wall surface of the grooveportion formed on the semiconductor substrate.
 3. The solid-stateimaging device according to claim 1, wherein a large part of the surfaceof the planar portion is covered with the first negative fixed chargefilm and a remaining part of the surface of the planar portion iscovered with the second negative fixed charge film on the planar portionon the light incident side of the semiconductor substrate.
 4. Thesolid-state imaging device according to claim 1, wherein a lightshielding film is formed on the groove portion formed on thesemiconductor substrate.
 5. The solid-state imaging device according toclaim 4, wherein the light shielding film is formed of aluminum (Al) ortungsten (W).
 6. The solid-state imaging device according to claim 1,wherein the solid-state imaging device is a backside illuminationcomplementary metal oxide semiconductor (CMOS) image sensor, a lightcondensing layer is formed on a back surface side of the semiconductorsubstrate, and a wiring layer is formed on a front surface side of thesemiconductor substrate.
 7. A manufacturing method comprising steps of:forming a groove portion in a depth direction from a light incident sideby etching for forming an element separating unit between adjacentphotoelectric conversion elements on a semiconductor substrate in whicha plurality of photoelectric conversion elements are formed; forming asecond fixed charge film according to an amount of damage received by aninner wall surface of the groove portion from the etching so as to coverthe inner wall surface of the groove portion formed on the semiconductorsubstrate, wherein the second fixed charge film is a second negativefixed charge film; and forming a first fixed charge film according to anamount of damage received by a planar portion from the etching so as tocover a surface of the planar portion on the light incident side of thesemiconductor substrate, wherein the first fixed charge film is a firstnegative fixed charge film, and wherein the second negative fixedcharged film is different from the first negative fixed charge film. 8.A manufacturing method comprising steps of: forming a first fixed chargefilm according to an amount of damage received by a planar portion frometching for forming a groove portion on a semiconductor substrate so asto cover a surface of the planar portion on a light incident side of thesemiconductor substrate in which a plurality of photoelectric conversionelements are formed, wherein the first fixed charge film is a firstnegative fixed charge film; forming the groove portion in a depthdirection from the light incident side by the etching for forming anelement separating unit between adjacent photoelectric conversionelements on the semiconductor substrate covered with the first fixedcharge film; and forming a second fixed charge film according to anamount of damage received by an inner wall surface of the groove portionfrom the etching so as to cover the inner wall surface of the grooveportion formed on the semiconductor substrate, wherein the second fixedcharge film is a second negative fixed charged film different from thefirst negative fixed charge film.
 9. An electronic device comprising: asolid-state imaging device including: a semiconductor substrate in whicha plurality of photoelectric conversion elements are formed; a grooveportion formed in a depth direction from a light incident side forforming an element separating unit between adjacent photoelectricconversion elements on the semiconductor substrate; a first fixed chargefilm formed according to an amount of damage received by a planarportion from etching for forming the groove portion on the semiconductorsubstrate so as to cover a surface of the planar portion on the lightincident side of the semiconductor substrate, wherein the first fixedcharge film is a first negative fixed charge film; and a second fixedcharge film formed according to an amount of damage received by an innerwall surface of the groove portion from the etching so as to cover theinner wall surface of the groove portion formed on the semiconductorsubstrate, wherein the second fixed charge film is a second negativefixed charge film different from the first negative fixed charge film.